As Solana is not EVM Compatible, you will need to use their Native Wallet, Phantom.
If you have not installed Phantom, you can download it on Chrome.
Head over to the Phantom download page and select your preferred option to download and follow the guide here.
After installation, you can now buy Solana ( SOL ) and fund your phantom wallet from your favorite exchanges such as Kucoin using the Solana Network by using your Phantom Wallet Address such as Kucoin in the example below.
Visit the official Raydium Website, please make sure to look at the URL as there are phishing sites that are similar to the official website.
Once you are on the website, click the "Connect Wallet" button on the top right corner and select Meta Mask.
Make sure to change the network on your Meta Mask to the Solana Network as well ( Meta Mask should prompt you )
Click on the "Select a Token" dropdown and find the token you want to swap for.
You can then swap your SOL for KKO in the Swap page as shown below. ( Keep some SOL for gas fees )
Do remember to set the slippage tolerance accordingly if there is any buy and sell tax involved or if liquidity is low.
If you can't find KKO in the swap, you can manually import it using the contract address.